1. XML "gauges" are typically in an MS Cabinet (.CAB) file.
2. You can use any unzip program to extract the files.
3. The name of the subfolder created is the main "gauge name."
4. The names of the individual XML files are the "subgauge names."
5. As you may know, gauges are listed in the panel.cfg file's entries in this form:
gauge
nn
=maingaugename!subgaugename, x,y,w,h
6. Simply rename the XML file to change the sub-gauge name, or the folder name to change the main gauge name.
7. Use the MS CAB utility program (cab.exe) to re-cab the folder.
8. edit the panel.cfg entries to update the names as necessary.